1 /* 2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 30 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 31 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 32 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp" 33 #include "gc_implementation/parallelScavenge/psOldGen.hpp" 34 #include "gc_implementation/parallelScavenge/psScavenge.hpp" 35 #include "gc_implementation/parallelScavenge/psYoungGen.hpp" 36 #include "gc_implementation/shared/gcHeapSummary.hpp" 37 #include "gc_implementation/shared/gcTimer.hpp" 38 #include "gc_implementation/shared/gcTrace.hpp" 39 #include "gc_implementation/shared/gcTraceTime.hpp" 40 #include "gc_implementation/shared/isGCActiveMark.hpp" 41 #include "gc_implementation/shared/markSweep.hpp" 42 #include "gc_implementation/shared/spaceDecorator.hpp" 43 #include "gc_interface/gcCause.hpp" 44 #include "memory/gcLocker.inline.hpp" 45 #include "memory/referencePolicy.hpp" 46 #include "memory/referenceProcessor.hpp" 47 #include "oops/oop.inline.hpp" 48 #include "runtime/biasedLocking.hpp" 49 #include "runtime/fprofiler.hpp" 50 #include "runtime/safepoint.hpp" 51 #include "runtime/vmThread.hpp" 52 #include "services/management.hpp" 53 #include "services/memoryService.hpp" 54 #include "utilities/events.hpp" 55 #include "utilities/stack.inline.hpp" 56 57 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 58 59 elapsedTimer PSMarkSweep::_accumulated_time; 60 jlong PSMarkSweep::_time_of_last_gc = 0; 61 CollectorCounters* PSMarkSweep::_counters = NULL; 62 63 void PSMarkSweep::initialize() { 64 MemRegion mr = Universe::heap()->reserved_region(); 65 _ref_processor = new ReferenceProcessor(mr); // a vanilla ref proc 66 _counters = new CollectorCounters("PSMarkSweep", 1); 67 } 68 69 // This method contains all heap specific policy for invoking mark sweep. 70 // PSMarkSweep::invoke_no_policy() will only attempt to mark-sweep-compact 71 // the heap. It will do nothing further. If we need to bail out for policy 72 // reasons, scavenge before full gc, or any other specialized behavior, it 73 // needs to be added here. 74 // 75 // Note that this method should only be called from the vm_thread while 76 // at a safepoint! 77 // 78 // Note that the all_soft_refs_clear flag in the collector policy 79 // may be true because this method can be called without intervening 80 // activity. For example when the heap space is tight and full measure 81 // are being taken to free space. 82 83 void PSMarkSweep::invoke(bool maximum_heap_compaction) { 84 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 85 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 86 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 87 88 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 89 GCCause::Cause gc_cause = heap->gc_cause(); 90 PSAdaptiveSizePolicy* policy = heap->size_policy(); 91 IsGCActiveMark mark; 92 93 if (ScavengeBeforeFullGC) { 94 PSScavenge::invoke_no_policy(); 95 } 96 97 const bool clear_all_soft_refs = 98 heap->collector_policy()->should_clear_all_soft_refs(); 99 100 uint count = maximum_heap_compaction ? 1 : MarkSweepAlwaysCompactCount; 101 UIntFlagSetting flag_setting(MarkSweepAlwaysCompactCount, count); 102 PSMarkSweep::invoke_no_policy(clear_all_soft_refs || maximum_heap_compaction); 103 } 104 105 // This method contains no policy. You should probably 106 // be calling invoke() instead. 107 bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) { 108 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 109 assert(ref_processor() != NULL, "Sanity"); 110 111 if (GC_locker::check_active_before_gc()) { 112 return false; 113 } 114 115 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 116 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 117 GCCause::Cause gc_cause = heap->gc_cause(); 118 119 _gc_timer->register_gc_start(); 120 _gc_tracer->report_gc_start(gc_cause, _gc_timer->gc_start()); 121 122 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 123 124 // The scope of casr should end after code that can change 125 // CollectorPolicy::_should_clear_all_soft_refs. 126 ClearedAllSoftRefs casr(clear_all_softrefs, heap->collector_policy()); 127 128 PSYoungGen* young_gen = heap->young_gen(); 129 PSOldGen* old_gen = heap->old_gen(); 130 131 // Increment the invocation count 132 heap->increment_total_collections(true /* full */); 133 134 // Save information needed to minimize mangling 135 heap->record_gen_tops_before_GC(); 136 137 // We need to track unique mark sweep invocations as well. 138 _total_invocations++; 139 140 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 141 142 heap->print_heap_before_gc(); 143 heap->trace_heap_before_gc(_gc_tracer); 144 145 // Fill in TLABs 146 heap->accumulate_statistics_all_tlabs(); 147 heap->ensure_parsability(true); // retire TLABs 148 149 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 150 HandleMark hm; // Discard invalid handles created during verification 151 Universe::verify(" VerifyBeforeGC:"); 152 } 153 154 // Verify object start arrays 155 if (VerifyObjectStartArray && 156 VerifyBeforeGC) { 157 old_gen->verify_object_start_array(); 158 } 159 160 heap->pre_full_gc_dump(_gc_timer); 161 162 // Filled in below to track the state of the young gen after the collection. 163 bool eden_empty; 164 bool survivors_empty; 165 bool young_gen_empty; 166 167 { 168 HandleMark hm; 169 170 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 171 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 172 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer->gc_id()); 173 TraceCollectorStats tcs(counters()); 174 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 175 176 if (TraceGen1Time) accumulated_time()->start(); 177 178 // Let the size policy know we're starting 179 size_policy->major_collection_begin(); 180 181 CodeCache::gc_prologue(); 182 Threads::gc_prologue(); 183 BiasedLocking::preserve_marks(); 184 185 // Capture heap size before collection for printing. 186 size_t prev_used = heap->used(); 187 188 // Capture metadata size before collection for sizing. 189 size_t metadata_prev_used = MetaspaceAux::used_bytes(); 190 191 // For PrintGCDetails 192 size_t old_gen_prev_used = old_gen->used_in_bytes(); 193 size_t young_gen_prev_used = young_gen->used_in_bytes(); 194 195 allocate_stacks(); 196 197 COMPILER2_PRESENT(DerivedPointerTable::clear()); 198 199 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 200 ref_processor()->setup_policy(clear_all_softrefs); 201 202 mark_sweep_phase1(clear_all_softrefs); 203 204 mark_sweep_phase2(); 205 206 // Don't add any more derived pointers during phase3 207 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); 208 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); 209 210 mark_sweep_phase3(); 211 212 mark_sweep_phase4(); 213 214 restore_marks(); 215 216 deallocate_stacks(); 217 218 if (ZapUnusedHeapArea) { 219 // Do a complete mangle (top to end) because the usage for 220 // scratch does not maintain a top pointer. 221 young_gen->to_space()->mangle_unused_area_complete(); 222 } 223 224 eden_empty = young_gen->eden_space()->is_empty(); 225 if (!eden_empty) { 226 eden_empty = absorb_live_data_from_eden(size_policy, young_gen, old_gen); 227 } 228 229 // Update heap occupancy information which is used as 230 // input to soft ref clearing policy at the next gc. 231 Universe::update_heap_info_at_gc(); 232 233 survivors_empty = young_gen->from_space()->is_empty() && 234 young_gen->to_space()->is_empty(); 235 young_gen_empty = eden_empty && survivors_empty; 236 237 BarrierSet* bs = heap->barrier_set(); 238 if (bs->is_a(BarrierSet::ModRef)) { 239 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; 240 MemRegion old_mr = heap->old_gen()->reserved(); 241 if (young_gen_empty) { 242 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 243 } else { 244 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 245 } 246 } 247 248 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 249 ClassLoaderDataGraph::purge(); 250 MetaspaceAux::verify_metrics(); 251 252 BiasedLocking::restore_marks(); 253 Threads::gc_epilogue(); 254 CodeCache::gc_epilogue(); 255 JvmtiExport::gc_epilogue(); 256 257 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 258 259 ref_processor()->enqueue_discovered_references(NULL); 260 261 // Update time of last GC 262 reset_millis_since_last_gc(); 263 264 // Let the size policy know we're done 265 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 266 267 if (UseAdaptiveSizePolicy) { 268 269 if (PrintAdaptiveSizePolicy) { 270 gclog_or_tty->print("AdaptiveSizeStart: "); 271 gclog_or_tty->stamp(); 272 gclog_or_tty->print_cr(" collection: %d ", 273 heap->total_collections()); 274 if (Verbose) { 275 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d", 276 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 277 } 278 } 279 280 // Don't check if the size_policy is ready here. Let 281 // the size_policy check that internally. 282 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 283 ((gc_cause != GCCause::_java_lang_system_gc) || 284 UseAdaptiveSizePolicyWithSystemGC)) { 285 // Calculate optimal free space amounts 286 assert(young_gen->max_size() > 287 young_gen->from_space()->capacity_in_bytes() + 288 young_gen->to_space()->capacity_in_bytes(), 289 "Sizes of space in young gen are out-of-bounds"); 290 291 size_t young_live = young_gen->used_in_bytes(); 292 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 293 size_t old_live = old_gen->used_in_bytes(); 294 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 295 size_t max_old_gen_size = old_gen->max_gen_size(); 296 size_t max_eden_size = young_gen->max_size() - 297 young_gen->from_space()->capacity_in_bytes() - 298 young_gen->to_space()->capacity_in_bytes(); 299 300 // Used for diagnostics 301 size_policy->clear_generation_free_space_flags(); 302 303 size_policy->compute_generations_free_space(young_live, 304 eden_live, 305 old_live, 306 cur_eden, 307 max_old_gen_size, 308 max_eden_size, 309 true /* full gc*/); 310 311 size_policy->check_gc_overhead_limit(young_live, 312 eden_live, 313 max_old_gen_size, 314 max_eden_size, 315 true /* full gc*/, 316 gc_cause, 317 heap->collector_policy()); 318 319 size_policy->decay_supplemental_growth(true /* full gc*/); 320 321 heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes()); 322 323 // Don't resize the young generation at an major collection. A 324 // desired young generation size may have been calculated but 325 // resizing the young generation complicates the code because the 326 // resizing of the old generation may have moved the boundary 327 // between the young generation and the old generation. Let the 328 // young generation resizing happen at the minor collections. 329 } 330 if (PrintAdaptiveSizePolicy) { 331 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 332 heap->total_collections()); 333 } 334 } 335 336 if (UsePerfData) { 337 heap->gc_policy_counters()->update_counters(); 338 heap->gc_policy_counters()->update_old_capacity( 339 old_gen->capacity_in_bytes()); 340 heap->gc_policy_counters()->update_young_capacity( 341 young_gen->capacity_in_bytes()); 342 } 343 344 heap->resize_all_tlabs(); 345 346 // We collected the heap, recalculate the metaspace capacity 347 MetaspaceGC::compute_new_size(); 348 349 if (TraceGen1Time) accumulated_time()->stop(); 350 351 if (PrintGC) { 352 if (PrintGCDetails) { 353 // Don't print a GC timestamp here. This is after the GC so 354 // would be confusing. 355 young_gen->print_used_change(young_gen_prev_used); 356 old_gen->print_used_change(old_gen_prev_used); 357 } 358 heap->print_heap_change(prev_used); 359 if (PrintGCDetails) { 360 MetaspaceAux::print_metaspace_change(metadata_prev_used); 361 } 362 } 363 364 // Track memory usage and detect low memory 365 MemoryService::track_memory_usage(); 366 heap->update_counters(); 367 } 368 369 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 370 HandleMark hm; // Discard invalid handles created during verification 371 Universe::verify(" VerifyAfterGC:"); 372 } 373 374 // Re-verify object start arrays 375 if (VerifyObjectStartArray && 376 VerifyAfterGC) { 377 old_gen->verify_object_start_array(); 378 } 379 380 if (ZapUnusedHeapArea) { 381 old_gen->object_space()->check_mangled_unused_area_complete(); 382 } 383 384 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 385 386 heap->print_heap_after_gc(); 387 heap->trace_heap_after_gc(_gc_tracer); 388 389 heap->post_full_gc_dump(_gc_timer); 390 391 #ifdef TRACESPINNING 392 ParallelTaskTerminator::print_termination_counts(); 393 #endif 394 395 _gc_timer->register_gc_end(); 396 397 _gc_tracer->report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions()); 398 399 return true; 400 } 401 402 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 403 PSYoungGen* young_gen, 404 PSOldGen* old_gen) { 405 MutableSpace* const eden_space = young_gen->eden_space(); 406 assert(!eden_space->is_empty(), "eden must be non-empty"); 407 assert(young_gen->virtual_space()->alignment() == 408 old_gen->virtual_space()->alignment(), "alignments do not match"); 409 410 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 411 return false; 412 } 413 414 // Both generations must be completely committed. 415 if (young_gen->virtual_space()->uncommitted_size() != 0) { 416 return false; 417 } 418 if (old_gen->virtual_space()->uncommitted_size() != 0) { 419 return false; 420 } 421 422 // Figure out how much to take from eden. Include the average amount promoted 423 // in the total; otherwise the next young gen GC will simply bail out to a 424 // full GC. 425 const size_t alignment = old_gen->virtual_space()->alignment(); 426 const size_t eden_used = eden_space->used_in_bytes(); 427 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 428 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 429 const size_t eden_capacity = eden_space->capacity_in_bytes(); 430 431 if (absorb_size >= eden_capacity) { 432 return false; // Must leave some space in eden. 433 } 434 435 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 436 if (new_young_size < young_gen->min_gen_size()) { 437 return false; // Respect young gen minimum size. 438 } 439 440 if (TraceAdaptiveGCBoundary && Verbose) { 441 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " 442 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 443 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 444 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 445 absorb_size / K, 446 eden_capacity / K, (eden_capacity - absorb_size) / K, 447 young_gen->from_space()->used_in_bytes() / K, 448 young_gen->to_space()->used_in_bytes() / K, 449 young_gen->capacity_in_bytes() / K, new_young_size / K); 450 } 451 452 // Fill the unused part of the old gen. 453 MutableSpace* const old_space = old_gen->object_space(); 454 HeapWord* const unused_start = old_space->top(); 455 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 456 457 if (unused_words > 0) { 458 if (unused_words < CollectedHeap::min_fill_size()) { 459 return false; // If the old gen cannot be filled, must give up. 460 } 461 CollectedHeap::fill_with_objects(unused_start, unused_words); 462 } 463 464 // Take the live data from eden and set both top and end in the old gen to 465 // eden top. (Need to set end because reset_after_change() mangles the region 466 // from end to virtual_space->high() in debug builds). 467 HeapWord* const new_top = eden_space->top(); 468 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 469 absorb_size); 470 young_gen->reset_after_change(); 471 old_space->set_top(new_top); 472 old_space->set_end(new_top); 473 old_gen->reset_after_change(); 474 475 // Update the object start array for the filler object and the data from eden. 476 ObjectStartArray* const start_array = old_gen->start_array(); 477 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 478 start_array->allocate_block(p); 479 } 480 481 // Could update the promoted average here, but it is not typically updated at 482 // full GCs and the value to use is unclear. Something like 483 // 484 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 485 486 size_policy->set_bytes_absorbed_from_eden(absorb_size); 487 return true; 488 } 489 490 void PSMarkSweep::allocate_stacks() { 491 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 492 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 493 494 PSYoungGen* young_gen = heap->young_gen(); 495 496 MutableSpace* to_space = young_gen->to_space(); 497 _preserved_marks = (PreservedMark*)to_space->top(); 498 _preserved_count = 0; 499 500 // We want to calculate the size in bytes first. 501 _preserved_count_max = pointer_delta(to_space->end(), to_space->top(), sizeof(jbyte)); 502 // Now divide by the size of a PreservedMark 503 _preserved_count_max /= sizeof(PreservedMark); 504 } 505 506 507 void PSMarkSweep::deallocate_stacks() { 508 _preserved_mark_stack.clear(true); 509 _preserved_oop_stack.clear(true); 510 _marking_stack.clear(); 511 _objarray_stack.clear(true); 512 } 513 514 void PSMarkSweep::mark_sweep_phase1(bool clear_all_softrefs) { 515 // Recursively traverse all live objects and mark them 516 GCTraceTime tm("phase 1", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id()); 517 trace(" 1"); 518 519 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 520 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 521 522 // Need to clear claim bits before the tracing starts. 523 ClassLoaderDataGraph::clear_claimed_marks(); 524 525 // General strong roots. 526 { 527 ParallelScavengeHeap::ParStrongRootsScope psrs; 528 Universe::oops_do(mark_and_push_closure()); 529 JNIHandles::oops_do(mark_and_push_closure()); // Global (strong) JNI handles 530 CLDToOopClosure mark_and_push_from_cld(mark_and_push_closure()); 531 MarkingCodeBlobClosure each_active_code_blob(mark_and_push_closure(), !CodeBlobToOopClosure::FixRelocations); 532 Threads::oops_do(mark_and_push_closure(), &mark_and_push_from_cld, &each_active_code_blob); 533 ObjectSynchronizer::oops_do(mark_and_push_closure()); 534 FlatProfiler::oops_do(mark_and_push_closure()); 535 Management::oops_do(mark_and_push_closure()); 536 JvmtiExport::oops_do(mark_and_push_closure()); 537 SystemDictionary::always_strong_oops_do(mark_and_push_closure()); 538 ClassLoaderDataGraph::always_strong_cld_do(follow_cld_closure()); 539 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them. 540 //CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure(mark_and_push_closure())); 541 } 542 543 // Flush marking stack. 544 follow_stack(); 545 546 // Process reference objects found during marking 547 { 548 ref_processor()->setup_policy(clear_all_softrefs); 549 const ReferenceProcessorStats& stats = 550 ref_processor()->process_discovered_references( 551 is_alive_closure(), mark_and_push_closure(), follow_stack_closure(), NULL, _gc_timer, _gc_tracer->gc_id()); 552 gc_tracer()->report_gc_reference_stats(stats); 553 } 554 555 // This is the point where the entire marking should have completed. 556 assert(_marking_stack.is_empty(), "Marking should have completed"); 557 558 // Unload classes and purge the SystemDictionary. 559 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 560 561 // Unload nmethods. 562 CodeCache::do_unloading(is_alive_closure(), purged_class); 563 564 // Prune dead klasses from subklass/sibling/implementor lists. 565 Klass::clean_weak_klass_links(is_alive_closure()); 566 567 // Delete entries for dead interned strings. 568 StringTable::unlink(is_alive_closure()); 569 570 // Clean up unreferenced symbols in symbol table. 571 SymbolTable::unlink(); 572 _gc_tracer->report_object_count_after_gc(is_alive_closure()); 573 } 574 575 576 void PSMarkSweep::mark_sweep_phase2() { 577 GCTraceTime tm("phase 2", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id()); 578 trace("2"); 579 580 // Now all live objects are marked, compute the new object addresses. 581 582 // It is not required that we traverse spaces in the same order in 583 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops 584 // tracking expects us to do so. See comment under phase4. 585 586 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 587 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 588 589 PSOldGen* old_gen = heap->old_gen(); 590 591 // Begin compacting into the old gen 592 PSMarkSweepDecorator::set_destination_decorator_tenured(); 593 594 // This will also compact the young gen spaces. 595 old_gen->precompact(); 596 } 597 598 // This should be moved to the shared markSweep code! 599 class PSAlwaysTrueClosure: public BoolObjectClosure { 600 public: 601 bool do_object_b(oop p) { return true; } 602 }; 603 static PSAlwaysTrueClosure always_true; 604 605 void PSMarkSweep::mark_sweep_phase3() { 606 // Adjust the pointers to reflect the new locations 607 GCTraceTime tm("phase 3", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id()); 608 trace("3"); 609 610 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 611 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 612 613 PSYoungGen* young_gen = heap->young_gen(); 614 PSOldGen* old_gen = heap->old_gen(); 615 616 // Need to clear claim bits before the tracing starts. 617 ClassLoaderDataGraph::clear_claimed_marks(); 618 619 // General strong roots. 620 Universe::oops_do(adjust_pointer_closure()); 621 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 622 CLDToOopClosure adjust_from_cld(adjust_pointer_closure()); 623 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL); 624 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 625 FlatProfiler::oops_do(adjust_pointer_closure()); 626 Management::oops_do(adjust_pointer_closure()); 627 JvmtiExport::oops_do(adjust_pointer_closure()); 628 SystemDictionary::oops_do(adjust_pointer_closure()); 629 ClassLoaderDataGraph::cld_do(adjust_cld_closure()); 630 631 // Now adjust pointers in remaining weak roots. (All of which should 632 // have been cleared if they pointed to non-surviving objects.) 633 // Global (weak) JNI handles 634 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure()); 635 636 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations); 637 CodeCache::blobs_do(&adjust_from_blobs); 638 StringTable::oops_do(adjust_pointer_closure()); 639 ref_processor()->weak_oops_do(adjust_pointer_closure()); 640 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 641 642 adjust_marks(); 643 644 young_gen->adjust_pointers(); 645 old_gen->adjust_pointers(); 646 } 647 648 void PSMarkSweep::mark_sweep_phase4() { 649 EventMark m("4 compact heap"); 650 GCTraceTime tm("phase 4", PrintGCDetails && Verbose, true, _gc_timer, _gc_tracer->gc_id()); 651 trace("4"); 652 653 // All pointers are now adjusted, move objects accordingly 654 655 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 656 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 657 658 PSYoungGen* young_gen = heap->young_gen(); 659 PSOldGen* old_gen = heap->old_gen(); 660 661 old_gen->compact(); 662 young_gen->compact(); 663 } 664 665 jlong PSMarkSweep::millis_since_last_gc() { 666 // We need a monotonically non-deccreasing time in ms but 667 // os::javaTimeMillis() does not guarantee monotonicity. 668 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 669 jlong ret_val = now - _time_of_last_gc; 670 // XXX See note in genCollectedHeap::millis_since_last_gc(). 671 if (ret_val < 0) { 672 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);) 673 return 0; 674 } 675 return ret_val; 676 } 677 678 void PSMarkSweep::reset_millis_since_last_gc() { 679 // We need a monotonically non-deccreasing time in ms but 680 // os::javaTimeMillis() does not guarantee monotonicity. 681 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 682 }